Color reversal photographic light-sensitive materials usually comprise a support having provided thereon at least two silver halide emulsion layers having a different color sensitivity (the term "color sensitivity" as used herein meaning the property of responding to one of the regions of the visible spectrum, e.g., to one of red, green and blue light).
In the field of color photographic light-sensitive materials, particularly color reversal light-sensitive materials popularly used among professional photographers, high speed color light-sensitive materials are required for photographing special scenes, such as sports scenes which require a high shutter speed, and stage scenes in which only an insufficient amount of light is generally available for exposure. However, few color photographic light-sensitive materials have a high enough speed to photograph such special scenes. Under such circumstances, the speed has been adjusted through some processing for supplementing the insufficient exposure of a color reversal film which has been taken photograph at higher speed than indicated speed of the film. This speed-adjusting processing is usually called "push processing", and, with color reversal light-sensitive materials, it is conducted by pushing first development (black-and-white development), for example, prolonging the period of first development longer than is employed in normal processing.
However, conventional color reversal light-sensitive materials do not have sufficient adaptability to the push processing, and thus exhibit the following defects:
(1) sufficient effect of increase in speed cannot be attained unless the period of first development is extremely prolonged in comparison with the normal processing; PA1 (2) with light-sensitive materials having a structure wherein the silver halide emulsion layer having specified color sensitivity is formed as two or more separate layers of unequal speed (e.g., a higher speed layer and lower speed layer), the push processing can lead to a change in gradation between the two or more layers due to the difference therebetween in adaptability to development processing; PA1 (3) prolongation of the period of first development for raising the degree of increase in speed can cause a serious decrease in color image density; or PA1 (4) push processing can cause deterioration of color balance due to the difference between the red-sensitive layer, green-sensitive layer and blue-sensitive layer in adaptability to development processing.
Thus, it has been desired to develop techniques which overcome the above-described defects and which enable full control of the degree of increase in speed without exerting any detrimental influence upon normal processing.
An object of the present invention is to provide the above-described techniques and color reversal photographic light-sensitive materials embodying them.
Japanese Patent Application (OPI) No. 128528/76 (corresponding to U.S. Pat. No. 4,082,553) (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") describes a color reversal light-sensitive material with an improved interimage effect which has a silver halide emulsion layer interspersed with surface-fogged silver halide grains that are distinctive from silver halide grains containing internal fog centers. However, addition of the surface-fogged silver halide grains adversely effects photographic properties in normal processing and seriously decreases color image density in push processing.
U.S. Pat. Nos. 2,996,382, 3,178,282 and 3,397,987 describe a negative image-forming photographic element of enhanced speed and contrast prepared by incorporating a combination of unfogged surface latent image silver halide grains and fogged internal latent image silver halide grains in an emulsion layer. However, these patents do not refer to push processing nor color reversal light-sensitive materials. Further, the element is designed so that, upon development after exposure, the unfogged surface latent image silver halide grains develop to liberate reaction products in proportion to an exposure amount, and then the reaction products crack the fogged internal latent image silver halide grains to render the grains developable. This element undergoes an increase in speed and contrast even upon normal processing, thus being unable to permit control of increase in speed by push processing.
Further, Japanese Patent Publication No. 19024/71 (corresponding to U.S. Pat. No. 3,505,068) describes a technique with respect to color reversal light-sensitive materials in which one or more emulsion layers of the same color sensitivity are formed as a combination of a higher speed layer and a lower speed layer, which technique comprises effectively decreasing contrast by using silver iodide in the higher speed layer and using grains of silver haloiodide core covered with completely silver iodide-free silver halide shell in the lower speed layer. However, the core-shell type silver halide grains used therein have no internal fog centers, and hence, they do not show any special action with respect to push processing.